docs: def aligned(e1, e2):
      """
      alignment is determined by two boxes having one exactly the same
      attribute, which could mean parallel, perpendicularly forming a
      corner etc.
      """
      return (
          any(close(c1, c2) for c1, c2 in zip(e1.bbox, e2.bbox))
          or x_center_aligned(e1, e2)
          or y_center_aligned(e1, e2)
      )